In electrophotography, a process called the Carlson process has been heretofore widely employed which comprises the steps of charging, exposure, development, transfer, destatizing and cleaning on a photoreceptor. In this process, a toner image developed is transferred to paper, and it is then fixed in a heat roll process or a pressure fixing process to obtain a final image thereon.
In order to simplify such an image formation process, it has been proposed to effect transfer and fixation at the same time. As the system using an amorphous silicon photoreceptor, the following processes have been proposed: JP-A55-87156 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") proposes a process in which a heat fixing roll is used to effect transfer and fixing of an image on a paper at the same time. JP-A-1-43954 proposes a process in which the transfer and fixation of an image are simultaneously effected by using an electrically conductive one-component toner.
However, the use of a heat fixing roll as proposed in JP-A-55-87156 is disadvantageous in that since the surface of the roll must be kept at a temperature as high as 180.degree. C., the heat fixing roll cannot be always brought into contact with a photoreceptor drum, and the photoreceptor drum requires a cooling apparatus, thus complicating the mechanism. Furthermore, this system is not suitable for continuous use. The use of pressure as proposed in JP-A-1-43954 is also disadvantageous in that since a high pressure is required to obtain a practical image, the photoreceptor may be destroyed when a cardboard paper is used or wrinkling occurs on a paper.
In order to obtain a sufficient fixing performance in this simultaneous transfer and fixing process, it is necessary that the adhesion of the toner used to the paper be strong enough. In such a case, the adhesion of the toner to the photoreceptor as well is strong. This renders the photoreceptor easily adherable to the paper or filmed on the surface thereof, causing poor transfer that results in image defects.